class_docstr: A pytorch module that is a wrapper for FrozenCLIPEmbedder module. it enhances FrozenCLIPEmbedder, making it possible to
  have unlimited prompt length and assign weights to tokens in prompt.
docstr: creates an empty PromptChunk and returns it
docstr_tok: ["creates","an","empty","PromptChunk","and","returns","it"]
code: def empty_chunk(self):
      """creates an empty PromptChunk and returns it"""
  
      chunk = PromptChunk()
      chunk.tokens = [self.id_start] + [self.id_end] * (
          self.chunk_length + 1
      )
      chunk.multipliers = [1.0] * (self.chunk_length + 2)
      return chunk
  
imports: import math
  from collections import namedtuple
  import torch
  from modules import prompt_parser, devices, sd_hijack
  from modules.shared import opts
label_desc: Use image node_id 2 for calling the FrozenCLIPEmbedderWithCustomWordsBase obj's underlying member method code with example usage: obj.empty_chunk() and returns: chunk